A study published Thursday found that nearly half of bald eagles examined across the US showed signs of chronic lead contamination.
While bald eagle populations have recovered from the brink of extinction since the United States banned the pesticide DDT in 1972, toxic levels of lead were found in the bones of 46% of bald eagles sampled in the United States. 38 states from California to Florida, the researchers said in the journal Science.
Similar rates of lead exposure were also found in golden eagles, which scientists say means raptors are more likely to eat carcasses or prey contaminated with lead from ammunition or fishing gear.
The blood, bones, feathers and liver tissue of 1,210 eagles sampled between 2010 and 2018 were examined to assess acute and chronic lead exposure.
Study co-author Todd Katzner, a wildlife biologist at the United States Geological Survey in Boise, Idaho, said: we were able to assess lead exposure and population-level consequences at a continental scale. . “It’s amazing that almost 50% of them are being repeatedly exposed to lead.”
Lead is a neurotoxin that even in low doses impairs balance and stamina, reducing its ability to fly, hunt and reproduce. In high doses, lead causes seizures, breathing problems, and death.
The study estimates that lead exposure reduces the annual population growth rates of bald eagles and golden eagles by 4% by 1%.
The bald eagle is one of the United States’ best-known conservation success stories, and the bird was removed from the U.S. Endangered Species List in 2007.
But scientists say high lead levels remain a concern. Besides preventing the eagles’ population growth, lead exposure reduces their resilience in the face of future challenges, such as climate change or infectious diseases. .
“When we talk about recovery, it’s not really the end,” said Krysten Schuler, a wildlife ecologist at Cornell University College of Veterinary Medicine who was not involved in the study. – there are still threats to bald eagles.
Previous studies have shown high levels of lead exposure in specific regions, but not nationally. Blood samples from live eagles in the new study were obtained from trapped birds and studied for other reasons; samples of bones, feathers, and livers from eagles killed by collisions with vehicles or power lines, or other bad luck.
Co-author Vince Slabe, a wildlife biologist at the nonprofit Conservation Science Global, said: “Lead is present in the landscape and is more readily available to these birds than to us. think. “A piece of lead the size of a pinhead is large enough to kill an eagle. ”
The researchers also found higher levels of lead exposure in the fall and winter, which coincide with hunting season in many states.
During these months, eagles search for carcasses and intestines left by hunters, which are often filled with lead shrapnel or shrapnel.
Slabe said the results of the study were not meant to disparage hunters. “Hunters are one of the best conservation groups in this country,” he said, noting that fees and taxes paid by hunters help fund state wildlife agencies and He also hunted deer and elk in Montana.
However, Slabe said he hopes the findings provide an opportunity to “talk to hunters about this matter explicitly” and that more hunters will voluntarily switch to lead-free ammunition. like copper bullets.
Lead ammunition for hunting waterfowl was banned in 1991, due to concerns about water contamination, and wildlife authorities encouraged the use of non-toxic steel shotguns. However, lead bullets are still popular for upland bird hunting and large game hunting.
Lead exposure levels vary by region, with the highest levels found on the Central Flyway, new research shows.
At the University of Minnesota’s Raptor Center, veterinarian and executive director Victoria Hall said “85 to 90% of the eagles that come to our hospital have some level of lead in their blood,” and X-rays often show lead shrapnel in their stomachs.
Eagles with relatively low levels can be treated, she said, but those with high exposure cannot be saved.
Laura Hale, board chair of the Badger Run Wildlife Rehab nonprofit in Klamath County, Oregon, said she will never forget the first eagle she encountered with acute lead poisoning, in 2018. She answered a resident’s call about an eagle that appeared to be motionless during grooming and brought it to the clinic.
The bald eagle was wrapped in a blanket, unable to breathe let alone stand or fly.
“There’s something disgusting about when you see an eagle struggling to breathe from lead poisoning – it’s really harsh,” she said, her voice trembling. That eagle had a convulsion and died within 48 hours.
Jennifer Cedarleaf, director of poultry at the Alaska Raptor Center, a nonprofit wildlife rescue organization in Sitka, Alaska, says landscape lead affects not only eagles, but many species other birds – including hawks, vultures, crows, swans and geese.
Because eagles are so sensitive to lead, are well researched, and have attracted so much public interest, “bald eagles are like canaries in a coal mine,” she says. “They’re the kind that tell us: We have a bit of a problem.”
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https://www.winknews.com/2022/02/18/nearly-half-of-us-bald-eagles-suffer-lead-poisoning/ Nearly half of bald eagles in the US are lead poisoning